Sewage fluid interface barrier

ABSTRACT

A sewer comprising a barrier disposed to prevent or reduce the flow of air in the headspace, oppose the escape of gases and/or liquid droplets from within the liquid into the headspace of the sewer, and also oppose the drawing in and entrainment of headspace air and gases into the liquid contained within the sewer. The sewer comprises a conduit and a barrier fixed within the interior of the sewer, which extends longitudinally along the sewer conduit so as to separate the sewer conduit into a liquid conductive channel disposed below the barrier and a gas conductive channel disposed above the barrier. The barrier may move up and down within the sewer responsively with varying water flow within the sewer. The barrier may comprise an elastomeric sheet. The barrier may be tubular at areas of steep plunge.

FIELD OF THE INVENTION

The present invention relates to sewers, and more particularly to improvements thereto for reducing interaction between liquid flow in a sewer and air occupying the space above the liquid level, referred to herein as the “headspace”, by imposing a physical barrier between liquid and air.

BACKGROUND OF THE INVENTION

Sanitary and storm sewers conduct fluent wastes away from infrastructure such as buildings and roads. Most sewers rely upon gravity to induce flow of fluent wastes. Both gravity operated and pressurized sewers are open to ambient air at one point or another. Sewers are susceptible to formation of objectionable gases and other substances which may be formed in fluent wastes and released to ambient air. Hydrogen sulfide is one such gas which arises from bacterial decomposition of organic materials such as sewage solids which are mixed with water to form a fluent mixture. Also, other substances and hydrocarbon compounds such as methane can form with other chemical products of sewage systems. Methane itself is a colorless odorless gas which is objectionable because it is flammable and because in sufficient quantity, it can displace oxygen. Sulfur and other compounds typically generate objectionable odors and may also be reactive and even toxic. Air within the headspace in sewers is dragged along by the flowing sewage resulting in airflow within the sewer headspace. Flowing air in the sewer headspace may result in sewer pressurization, particularly at locations where there is a change in sewer cross section, junctions, changes in longitudinal slope, inverted siphons, and other obstacles to sewer air flow. This in turn causes the sewer air and its objectionable gases to be forced out of the sewer into the surrounding atmosphere and neighborhoods.

In addition, flowing sewer air becomes entrained with liquid sewage, particularly at locations where liquid sewage falls steeply or vertically into downstream sewers or standing liquid sewage. Downstream of such locations, increased turbulence from energy dissipation results in increased sewer pressurization accompanied with sewage aerosol droplets and release of entrained air. This, in turn, causes increased potential for the release of sewer air and its objectionable gases to the surrounding atmosphere and neighborhoods.

Sewers typically extend for long distances and in so doing pass by many occupied buildings. Release of objectionable gaseous or gas borne contaminants into the ambient air near these buildings is objectionable, and occurs if no steps are taken to prevent this from happening. A mixture of sewer air, hydrogen sulfide, methane, and diverse chemical contaminants escaping from a sewer system and entering into areas of human activity is objectionable and intolerable.

Sewer air treatment facilities have been developed to remove and treat the liquid borne gases from the sewer air. While such facilities have been proven relatively effective at removing the objectionable gases from the sewer air, they are treating the symptom and not dealing with the underlying causes, which is the flow of air in the headspace and its contamination with sewage born gases. Another approach has been to use chemicals for neutralizing sewage components that generate the objectionable gases. However, these require extensive and continuous use of potentially harmful chemical that must be used in proportion to need, can be depleted by reacting with sewage before the entire length of the sewer has been remediate by chemical neutralization, and may also be depleted by evaporation or entrainment with gases escaping from liquid sewage.

There remains a need for eliminating or reducing the flow of air in the headspace of sewers, its contamination with sewage borne gases, and entrainment and re-release of sewer air into and out of liquid sewage within sewer conduits.

SUMMARY OF THE INVENTION

The present invention provides an answer to the above stated need by interposing a physical barrier between liquid sewage and the headspace thereabove. The barrier may be flexible and movable in a direction perpendicular to liquid flow so as to accommodate fluctuations in volume of flow while still providing the barrier function.

The barrier may for example take the form of a flexible water impermeable, gas impermeable blanket which spans the interior diameter of an associated sewer conduit and is supported at least at one end within the sewer conduit so as to rest on liquid sewage occupying the sewer conduit. The end opposite that which is supported may be unattached to the sewer conduit or alternatively may be supported within the sewer conduit. The blanket may isolate the liquid sewage from air occupying the headspace above the liquid sewage. This will both oppose the air within the headspace from being dragged along into the liquid sewage that establishes a current of air within the headspace, and will also prevent the sewer air from being drawn in and entrained in the sewage. It will further entrap and oppose escape of gases and sewage droplets which may come out of suspension within the liquid sewage or be sprayed out at locations of turbulence. All of these occurrences will assist in preventing fouling of ambient air outside yet near the sewer.

The barrier may be arranged to rise and fall within a sewer conduit for example, to accommodate fluctuations in depth of liquid sewage.

The barrier may be formed in serial sections to collectively cover long expanses of sewer. Each of these serial sections may be independently supported to the interior wall of the sewer.

The barrier may be of floatable material itself or portions of the barrier may incorporate floats to assure that the barrier remain above liquid contained within the sewer.

The barrier may be formed with some portions along which the barrier forms a sheet and others wherein the barrier forms a tube. The latter situation may come into play at locations where the sewer undergoes a vertical or steep non-vertical plunge or the like. In such situations, the barrier may be tubular, so as to conduct liquid sewage past the plunge. In such situations, sheet construction of the barrier could potentially interfere with intended operation.

It is an object of the invention to provide a barrier at the liquid-to-gas interface within a sewer for opposing drag-induced air flow and migration of gases along the headspace of the sewer and also opposing drawing of headspace gases into entrainment within the liquid as well as preventing the release of entrained gases within the sewage.

It is an object of the invention to provide improved elements and arrangements thereof by apparatus for the purposes described which is relatively inexpensive, dependable, and fully effective in accomplishing its intended purposes.

These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

FIG. 1 is a cross sectional view of a sewer construction according to at least one aspect of the invention.

FIG. 2 is a cross sectional view taken along line 2-2 in FIG. 1.

FIG. 3 is a cross sectional view similar to FIG. 2, but showing a slightly decreased volume flow of liquid contained within the sewer construction from that of FIG. 1.

FIG. 4 is a cross sectional view similar to FIG. 2, but showing a slightly increased volume flow of liquid contained within the sewer construction from that of FIG. 1.

FIG. 5 is a cross sectional view similar to FIG. 2, but showing the sewer construction entirely filled with liquid.

FIG. 6 is a cross sectional view similar to FIG. 1, but showing a greater length of the subject sewer construction.

FIG. 7 is a cross sectional view of a sewer construction according to the tubular aspect of the invention, wherein there is an abrupt change in elevation of the system.

DETAILED DESCRIPTION

Referring first to FIG. 1, there is shown a sewer construction according to at least one aspect of the invention wherein the sewer construction is provided with a barrier preventing the imposition of drag forces at the surface of flowing liquid 102 in sewer 100, upon the air within the sewer headspace 104, thereby preventing the flow of air in the headspace. The barriers is also opposing the escape of gases and droplets (not visible) generated within liquids 102 contained within the sewer 100 into the headspace 104 of the sewer 100 and also opposing the drawing in and entrainment of headspace air and gases into the liquid 102 contained within the sewer 100. The sewer 100 will be understood to be a system comprising of at least one sewer conduit 106 and ancillary components such as a manhole, a vent, or another sewer 108 which opens to the exterior of the sewer 100 to permit air and or liquids to enter the sewer 100.

The sewer conduit 106 is typically made from concrete, cast iron, steel, brick, and other durable substances, and comprises a circumferential wall 110 for confining liquids such as the liquid 102 within the sewer 100 and a longitudinal axis 112. The liquid 102 may be any liquid intended to be collected for conveyance and/or disposal, such as water from rainfall, domestic wastewater containing solid waste, or any liquid which is collected in a system which is open to the environment as opposed to a sealed system such as a pressurized domestic water supply. The sewer conduit 106 may have an entry opening 114 such as that shown formed in the manhole or vent 108. The entry opening opens the interior of the circumferential wall 110 to the environment, for allowing access to the interior of the sewer for maintenance, enabling inflow or outflow of air, or enabling collection of liquids to be discharged. The sewer 100 terminates in a discharge opening (not shown) for discharging collected liquids contained within the sewer conduit 106 to the exterior thereof, such as the head works of a sewage treatment plant.

The sewer conduit 106 is provided with a suitable support mechanism for fixing or holding the barrier in operable position within the interior of the sewer conduit 106. The barrier may comprise an elastomeric sheet 116 for example. It is preferred that the barrier be gas impermeable, water impermeable, and flexible. Many available elastomeric substances such as natural and synthetic rubbers and plastics, among others, satisfy these demands and are suitable for forming the barrier. The support mechanism may comprise a hoop 118 provided with an pivotally supported arm 124 pivotally anchored to the hoop 118 at a swivel joint 122. The arm 124 may comprise a clamp 120 for grasping the elastomeric sheet 116. Of course, the support structure may take any convenient form such that it solidly engages the circumferential wall 110 and reliably holds the barrier. Similarly, the arm 124 may be replaced by different arrangements, including but not limited to the direct fastening of the barrier blanket itself to the wall of the sewer.

The barrier is disposed to extend longitudinally along the sewer conduit 106, generally parallel to the longitudinal axis 112. Most sewer systems are gravity operated, and are built with slight inclination from a purely horizontal direction to promote flow in a desired direction. Therefore, the support mechanism is located upstream from the barrier where the barrier may be supported at only one end. As will be described hereinafter, it is possible to support the barrier at more than just one point.

The barrier separates the sewer conduit into a liquid conductive channel disposed below the barrier for conducting the liquid 102, and a gas conductive channel disposed above the barrier. It will be understood that the air conductive channel, which comprises the headspace 104 and the liquid conductive channel, which is that space occupied by the liquid 102, are to be regarded as semantic distinctions as these channels are not separate physical elements unto themselves. Rather, the channels refer to the spaces occupied respectively by air 104 and by the liquid 102. These spaces or volumes vary with the flow of the liquid 102, as flow refers to volume of the liquid 102 occupying the sewer 100. To facilitate this variation while simultaneously performing its function of segregating the liquid 102 from gases of the headspace 104, the barrier is disposed to move radially with respect to the longitudinal axis 112. That is, the barrier may be located at any of many points ranging from proximate the bottom of the sewer conduit 106 to proximate the top thereof, as seen in FIG. 1.

It should be noted at this point that orientational terms such as top and bottom refer to the subject drawing as viewed by an observer. The drawing figures depict their subject matter in orientations of normal use, which could obviously change with different sewer systems. Therefore, orientational terms must be understood to provide semantic basis for purposes of description, and do not limit the invention or its component parts in any particular way.

The motion of the barrier is enabled by a pivotal connection 120 of the arm 124. The pivotal connection 120 enables the arm 124 to swing in an arcuate motion through an arc 126. Of course, the arm 124 could be replaced by a linearly moving device for example or other arrangement provided it enables the barrier to track height of the liquid 102 within the sewer conduit 106, including the barrier blanket itself. Any motion which effectively enables the barrier to track height of the liquid 102 will be referred to as radial motion as that motion extends in directions which radiate from the longitudinal axis 112.

The barrier may also have the characteristic that it responds spontaneously to variations in the height or volume of the liquid 102. Where the barrier is provided by the elastomeric sheet 116, it will be seen that with the elastomeric sheet 116 secured to the sewer conduit 106 at a fixed point, the liquid 102 itself and gravity will combine to impose forces which raise and lower the elastomeric sheet 116 with rising and falling flow or volumes of the liquid 102. This action is spontaneous in that no external controls or motive forces need be applied to cause the elastomeric sheet 116 to accommodate variation in flow or volume.

FIG. 2 shows the elastomeric sheet 116 spanning the interior diameter of the sewer conduit 106, as it would with the liquid 102 occupying about half of the total cross sectional area of the sewer conduit 106.

Variations of height of the liquid 102 within the sewer conduit 106 may be accommodated in part by the ability of the elastomeric sheet 116 to have its edges 128, 130 turn upwardly (FIG. 3) or downwardly (FIG. 4) as the volume of the liquid 102 varies. FIG. 5 shows how the elastomeric sheet 116 may deflect should the sewer conduit 106 fully fill with the liquid 102.

FIG. 6 shows a serial arrangement of barrier elements within a sewer construction 200. It will be appreciated that as the elastomeric sheet 116 becomes longer and longer, installation, removal, and maintenance thereof become increasingly problematic. Extremely long runs of elastomeric sheet 116 may cause problems in orderly operation, such as twisting or other deformations which could prevent effective operation. To forestall such problems, the barrier may be formed in repeating sections.

The sewer construction 200 may comprise a sewer conduit 206 in which a first elastomeric sheet 216A and a second elastomeric sheet 216B are provided serially so as to provide essentially continuous coverage of the liquid 202 contained within the sewer conduit 206 apart from minor gaps which may be present therebetween, particularly at junctions and locations of lateral inflow by other sewers. Each barrier element such as the elastomeric sheets 216A, 216B may be secured at the top of the sewer conduit 206 by respective support mechanis, which may comprise a hoop such as the hoop 118 of FIG. 1, or which may take other forms. Regardless of its form, the support structure may include a swivel 222A or 222B for pivotally anchoring a respective arm 224A or 224B comprising a respective clamp 220A or 220B adapted to engage and operably support its respective elastomeric sheet 216A or 216B, which may be continuous as shown or in distinct separate sections. The respective clamp 220A or 220B may simply be the direct fastening of the respective elastomeric sheet 216A or 216B to the sewer. The serial arrangement of barrier elements depicted in FIG. 6 may be extended along the entirety of the sewer conduit 206 to implement a sewer construction 200 protected along its entire length against interaction of headspace gases and the liquid 202.

Flow of the liquid 202 is in a direction indicated by an arrow 228. It will be seen that the swivels 222A, 222B are located upstream with respect to flow of the liquid 202 from their respective elastomeric sheets 216A, 216B. Spacing of the swivels 222A, 222B and the respective elastomeric sheets 216A, 216B from one another may be modified to suit conditions so as to minimize any portion of the liquid 202 which may be exposed to the headspace 204 between adjacent elastomeric sheets 216A, 216B.

FIG. 7 shows further aspects of the invention. In FIG. 7, a sewer construction 300 includes an abrupt drop in elevation wherein a first generally horizontal section 306 of sewer conduit communicates with a vertical section 340 of sewer conduit, which in turn communicates with a second generally horizontal section 342 of sewer conduit. The sewer construction 300 copes with this abrupt drop by providing a barrier which negotiates the expanse of drop is in the form of a tube 344.

It will be seen that the distal end 346 of a barrier element in the form of a sheet 348, the same configuration as the elastomeric sheet 116 of FIG. 1, may terminate at the same anchorage point 350 as that used to support a proximal end 352 of the tube 344, or may terminate either downstream or upstream of point 350 as appropriate or deemed necessary by practical considerations. The tube 344 may be supported about the full circumference of its proximal end by a hoop structure 354 formed as part of that structure providing the anchorage point 350. The tube 344 may distend and collapse depending upon the volume of liquid 302 flowing therethrough at any one time. The tube 344 may be superseded by another sheet barrier element (not shown) at the distal termination (not seen in FIG. 7) of the tube 344. The sewer construction 300 may be summarized as comprising a barrier which in turn comprises a sheet (such as the sheet 348) along some of the length of the associated sewer conduit assembly (comprising for example the sewer conduits 306, 340, and 342) and a tube (such as the tube 344) along other portions of the length of the sewer conduit assembly. Although the sewer conduits 306, 340, 342 may be provided in sections for ease of fabrication and assembly, it will be recognized that after assembly, they collectively form a single sewer conduit.

The invention may also be considered a method of operating a sewer which contains both liquid and also air within a headspace located above the liquid. The method may comprise a fundamental step of providing a barrier within the sewer along a portion or the majority of the length of the sewer, which barrier extends longitudinally along the sewer and is interposed between the liquid contained within the sewer and the air of the headspace.

The method may also include the steps of anchoring a first end of the barrier at a fixed point within the sewer, anchoring a second end of the barrier at a fixed point within the sewer, enabling the barrier to move radially with respect to the longitudinal axis of the sewer so as to vary the respective volumes of the sewer above the barrier and below the barrier, and causing the barrier to move radially with respect to the longitudinal axis of the sewer spontaneously responsive to the volume of liquid contained within the liquid conductive channel.

The steps of the method refer to apparatus shown and described with connection to FIGS. 1-7. The steps may be practiced in any feasible order and combination independently of other steps.

Although presented in terms of a sewer the usual purpose of which is to dispose of storm water or sewage or both, the present invention is obviously adaptable to the purpose of other liquid systems which rely on gravity for at least a portion of their extent. For example, irrigation and liquid transfer systems, canals, tunnels and other liquid transport and conveyance systems, fire suppression systems, and still others will be understood to fall within the scope of the term “sewer” as employed herein.

The present invention is susceptible to modifications and variations which may be introduced thereto without departing from the inventive concepts. For example, a barrier or a portion thereof may be rigid rather than flexible. Sewer conduits may be oblong, rectangular, or otherwise configured in cross section (such as the cross section shown in FIG. 2.

While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is to be understood that the present invention is not to be limited to the disclosed arrangements, but is intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible. 

1. A sewer construction provided with a barrier to prevent or reduce the dragging of the air within the sewer headspace by the flowing liquids thereby preventing or reducing the flow of air in the headspace, opposing the escape of dissolves gases and/or liquid droplets from the liquids into the headspace of the sewer, and also opposing the drawing in and entrainment of headspace air and gases into the liquid contained within the sewer, comprising: a sewer conduit having a circumferential wall for confining liquids within the sewer and a longitudinal axis, and comprising at least one entry opening which opens the interior of the circumferential wall to the environment, for allowing access to the interior of the sewer for maintenance, enabling inflow or outflow of air, or enabling collection of liquids to be discharged, and a discharge opening for discharging collected liquids contained within the sewer conduit to the exterior of the sewer conduit; and a barrier fixed to the sewer conduit within the interior of the sewer conduit, wherein the barrier is disposed to extend longitudinally along the sewer conduit and to separate the sewer conduit into a liquid conductive channel disposed below the barrier for conducting liquids and a gas conductive channel disposed above the barrier, wherein the barrier is disposed to move radially with respect to the longitudinal axis so as to vary the respective volumes of the liquid conductive channel and the gas conductive channel.
 2. The sewer construction of claim 1, wherein the barrier is disposed to move radially with respect to the longitudinal axis so as to vary the respective volumes of the liquid conductive channel and the gas conductive channel spontaneously responsive to the volume of liquid contained within the liquid conductive channel.
 3. The sewer construction of claim 1, wherein the barrier comprises a flexible material.
 4. The sewer construction of claim 1, wherein the barrier is partially liquid impermeable.
 5. The sewer construction of claim 1, wherein the barrier is fully liquid impermeable.
 6. The sewer construction of claim 1, wherein the barrier is partially gas impermeable.
 7. The sewer construction of claim 1, wherein the barrier is fully gas impermeable.
 8. The sewer construction of claim 1, wherein the barrier comprises a sheet.
 9. The sewer construction of claim 1, wherein the barrier comprises a sheet along some of the length of the sewer conduit and a tube along other portions of the length of the sewer conduit.
 10. The sewer construction of claim 9, wherein the barrier comprises a sheet along its entire length.
 11. The sewer construction of claim 9, wherein the barrier comprises a tube along its entire length.
 12. A method of operating a sewer which contains both liquid and also air within a headspace located above the liquid, comprising the steps of: providing a barrier within the sewer along at least a portion of the length of the sewer, which barrier extends longitudinally along the sewer and is interposed between the liquid and the air of the headspace.
 13. The method of claim 12, comprising the further step of anchoring a first end of the barrier at a point within the sewer.
 14. The method of claim 13, comprising the further step of anchoring a second end of the barrier at a second point within the sewer
 15. The method of claim 12, comprising the further step of enabling the barrier to move radially with respect to the longitudinal axis of the sewer so as to vary the respective volumes of the sewer above the barrier and below the barrier.
 16. The method of claim 15, comprising the step of causing the barrier to move radially with respect to the longitudinal axis of the sewer spontaneously responsive to the volume of liquid contained within the liquid conductive channel. 